1. Field
Embodiments described herein relate generally to data storage units, systems and methods for storing data in a hybrid disk drive.
2. Description of the Related Art
Hybrid hard disk drives (HDDs) include one or more rotating magnetic disks combined with non-volatile solid-state (e.g., flash) memory. Generally, a hybrid HDD has both the capacity of a conventional HDD and the ability to access data as quickly as a solid-state drive, and for this reason hybrid drives are expected to be commonly used in laptop computers.
However, the solid-state memory in hybrid drives generally suffers from the same sensitivity to high and low temperatures as that associated with solid-state drives. For example, memory cells in NAND-based solid-state drives are only operable for a limited number of program/erase cycles, and this number is greatly reduced when program/erase cycles are performed extensively at low temperatures. Thus, operation of a hybrid drive at temperatures lower than the optimal operating temperature range of the NAND memory can undesirably shorten the useful life of the NAND portion of the drive. Furthermore, at higher temperatures, data retention of NAND memory cells is greatly reduced. At very high temperatures, for example when a solid-state drive is greater than 60 to 80° C., even short-term retention of data of NAND memory cells may become unreliable, and the NAND memory cells cannot be considered a dependable non-volatile data storage medium. This is because, in such situations, data stored in NAND memory cells may be lost at anytime. So while hybrid drives can incorporate some of the advantages of solid-state drives, hybrid drives also have some of the same shortcomings.